1. Field of the Invention
This invention relates to a method of decomposing a thermosetting resin, and to an apparatus and a heat control program for carrying out the method.
2. Description of the Background
Discarded electric household appliances provide one example of waste matters comprising a thermosetting resin. In recent years, it has been increasingly requested to recycle discarded electric household appliances. With a view to responding to such requests, it is now extensively studied to discover methods of recycling discarded electric household appliances by examining each of their components. In the disposal of discarded refrigerators, for example, since foamed urethane resin is employed therein as a heat-insulating material, the recycle of the urethane resin is studied now.
As for the method of recycling foamed urethane resin, there have been proposed various methods in the past. For example, Japanese Patent Unexamined Publication H6-184513 sets forth a method wherein a thermosetting resin comprising soft or hard polyurethane foam is decomposed at a constant temperature ranging from 150 to 280° C. using aminoethanol as a decomposer.
However, this method is problematical in that it takes a lot of time for decomposing the polyurethane foam, e.g., 11 hours at a temperature of 190° C., 2 hours even at a higher temperature of 230° C., and that under some circumstances, it is impossible to completely decompose the thermosetting resin. The reason for this may be attributed to the fact that the decomposer is not necessarily fully effective. Specifically, when the thermal decomposition of the thermosetting resin is immediately started at this range of temperatures, the heating is initiated at a temperature which is higher than the boiling point of the decomposer, such as aminoethanol. As a result, the decomposer is forced to volatilize before it is sufficiently mixed with the thermosetting resin, thus making it impossible to perform the kneading of the decomposer with the thermosetting resin at a constant mixing ratio, thereby inviting a phenomenon where the decomposing reaction of the thermosetting resins is inhibited.
This invention has been accomplished under the circumstances as mentioned above, and therefore, an object of this invention is to provide a method of decomposing thermosetting resins, which makes it possible to shorten the time required to decompose thermosetting resins, and to completely decompose thermosetting resins.
Another object of this invention is to provide an apparatus for decomposing thermosetting resins using the aforementioned method.
A further object of this invention is to provide a control program for the method of decomposing thermosetting resins.